Ben Cherington never really had a chance to overhaul his starting rotation this winter ó not if he didnít want to sell low on Jon Lester and give away John Lackey.

Ben Cherington never really had a chance to overhaul his starting rotation this winter ó not if he didnít want to sell low on Jon Lester and give away John Lackey. Cherington instead will go into spring training with his five starters set ó Lester and Lackey will be joined by Clay Buchholz, Felix Doubront and free-agent acquisition Ryan Dempster.

What remains to be determined is how effective the starting rotation will be. But maybe a more important question should be asked first: How effective does the rotation have to be?

To contend, if last season is any indication, Boston needs one or two pitchers ó most likely Buchholz and/or Lester ó to pitch like All-Stars. Beyond that, however, recent history says the Red Sox would be fine even with slightly below-average performances from the rest of the rotation.

No reasonable Red Sox fan expects a starting rotation with five Cy Young candidates. But the five starters Boston sent to the mound last season ó Buchholz, Doubront, Lester, Josh Beckett and Aaron Cook ó all were below-average pitchers. Among American League teams, only Cleveland and Minnesota saw their starters compile a worse ERA than the 5.19 ERA Red Sox starters did.

Baseball-Reference.comís adjusted ERA+ is a relatively simple measure of pitcher performance. ERAs are weighted for ballpark ó a pitcher inherently will give up more runs in Yankee Stadium than Petco Park ó and era. Average is defined as 100. A pitcher with an ERA+ of 110 is 10 percent better than average, accounting for ballpark and era.

Of the nine pitchers who made starts for the Red Sox last season, only Franklin Morales finished the season with an ERA+ higher than 100. Buchholz had an ERA+ of 95, Lester 90, Doubront 89. Beckett had an ERA+ of 83 when he was traded. Cook finished the season with an ERA+ of 77, which would have ranked him 84th in the major leagues had he qualified.

Common sense suggests that teams canít contend with below-average pitchers. To an extent, thatís true.

But an examination of the 10 teams that made the playoffs last season reveals that not every team had average or above-average pitching across the board. Of those 10 teams, only the Oakland Athletics saw their top five pitchers all finish with an ERA+ of 100 or above. Each of the other nine had to compensate for at least one below-average pitcher ó and often more than one.

The World Series champion San Francisco Giants had to absorb 33 starts from Tim Lincecum and his 5.18 ERA. Considering that the Giants play in a pitcher-friendly home ballpark and in a pitcher-friendly division, Lincecumís 5.18 ERA works out to the same ERA+ as John Lackeyís 6.41 ERA in his horrific 2011 season ó both 67, or 33 percent below average.

Three other playoff teams had to contend with three below-average starters in their rotations ó Atlanta, St. Louis and the Yankees. For the Yankees, Phil Hughes had an ERA+ of 99, while Ivan Nova and Freddy Garcia had an ERA+ of 83 and 80, respectively.

How were those teams able to stay afloat? Their rotations were top-heavy. New York won the American League East thanks to Hiroki Kuroda (ERA+ of 126) and CC Sabathia (124) and, to a lesser extent, Andy Pettitte and David Phelps (146 and 125, respectively). San Francisco won the National League West thanks in large part to Cainís ERA+ of 125. St. Louis and its otherwise mediocre rotation would have gone nowhere without Kyle Lohse and his ERA+ of 134.

In stark contrast to the Red Sox, all 10 of the playoff teams had at least one starter post an ERA+ higher than 120, a mark reached by only 22 qualifying starters in the major leagues. The Washington Nationals rode Gio Gonzalez (137), Jordan Zimmermann (134) and Stephen Strasburg (125) to the best record in the major leagues.

Can Buchholz and Lester reach that lofty territory next season? Both have done so in the recent past.

Buchholz posted an ERA+ of 187 in 2010, best in the American League. He followed that up with an ERA+ of 124 in his injury-shortened 2011 season.

Lester had been even more reliable before last season. He compiled an ERA+ of 144 in his first full major-league season and followed that up with marks of 136, 134 and 124 before sinking to unprecedented depths a year ago.

Dempster and Lackey have been at least average pitchers on a consistent basis, too.

The first season Lackey pitched in Boston, a season in which his $18-million salary made him a lightning rod, his ERA+ was 99 ó almost exactly average. Before that, Lackey posted an ERA+ of 115 or higher in each of his final five seasons with the Los Angeles Angels of Anaheim.

For his part, Dempster has posted an ERA+ under 110 only once in the last five seasons. His ERA+ for last season was 124, a mark that even includes his horrific first two weeks with the Texas Rangers in August.

Boston doesnít figure to come close to Oakland or Washington in terms of quality of starting rotation. But if the Red Sox can get three average performances and one or two All-Star-caliber performances from their five starters, thatís enough to contend.